proton plan

Proton PlanProton Plan

Eric PrebysFNAL Accelerator Division

Proton Plan, September 21st, 2004 - Prebys 2

““Proton Plan”Proton Plan” The details of proton demand and issues can be found in

an official report to the director at: www.fnal.gov/directorate/program_planning/studies/ProtonReport.pdf

Working assumptions: Existing proton source must last at least another 10 years or

so in more or less it’s current configuration. During that time, a new “proton driver” will be built, which

will ultimately replace the existing proton source. Proton source improvements should require no significant

downtimes beyond those needed for other reasons. The maximum total funding for proton source improvements

will be of the order of $18M over the next few years. Near term projects most important to performance


Scope of ImprovementsScope of Improvements The level of funding precludes some things

which have been discussed: Replacement or major upgrade of 200 MHz linac

• Official policy on 7835 PA’s: keep fingers crossed. Decrease of Main Injector ramp time

• Unless it is done as part of Proton Driver For this reason, the proton plan focuses

primarily on the Booster Decreasing uncontrolled losses. Increasing reliable average repetition rate. Biggest decisions involve plan for RF system.


What Limits Total Proton Intensity?What Limits Total Proton Intensity? Maximum number of Protons the Booster can stably

accelerate: 5E12 Maximum average Booster rep. Rate: currently 7.5 Hz,

may have to go to 10 Hz for NuMI+ (full) MiniBooNE (NUMI only) Maximum number of booster batches the

Main Injector can hold: currently 6 in principle, possibly go to 11 with fancy loading schemes in the future

(NUMI only) Minimum Main Injector ramp cycle time (NUMI only): 1.4s+loading time (at least 1/15s*nbatches)

Losses in the Booster: Above ground radiationDamage and/or activation of tunnel

components Our biggest worry at the moment!!!!


Early EffortsEarly Efforts Shielding and reclassifying Booster towers. More sophisticated loss monitoring methods. Extraction notch:

Kick notch in beam early in cycle to reduce loss at extraction.

Install ramped corrector system. Used to reduce losses at specific locations. Ultimately limited by corrector strength.

Replace Long 3 extraction septum and power supply: Increase maximum average rep. rate.

Increase efforts to understand the physics of the Booster.


Booster Modeling EffortsBooster Modeling Efforts At the beginning of 2001:

The transverse lattice model for the Booster was the ideal lattice of TM-405:

• No correctors• No injection or extraction elements• No higher order moments• Etc.

There was no realistic longitudinal model. It was believed that space charge at injection was a

significant problem. A group formed to study… Now:

Transverse model includes• All correctors• All injection and extraction elements• Body multipoles• Alignment data

Detailed longitudinal model, verified by measurement. Believable space charge simulations, verified by

measurements.


Results of Modeling EffortsResults of Modeling Efforts Space charge effects, while present, do not

appear to be a huge effect. Larger Issues:

Dogleg effect.• Distortion at injection cause by extraction doglegs.• Major discovery. Became focus of our efforts.

Beam motion:• Misalignment• Limited correctors• Horizontal slewing due to underpowered injection bump

magnets (ORBUMP). RF Power limitations:

• Existing RF marginal to get beam through transition.


Big Improvements in the Last YearBig Improvements in the Last Year Primary extraction “dogleg fix”

Increase spacing between magnets in chicane system

Reduces distortion to injection lattice by ~40% Vertical alignment

Eliminate ¼” misalignment at collimator region Improve high field orbit

400 MeV line work Better understanding Improved stability and repeatability

Injection bump (ORBUMP) improvements Improved water flow New, lower resistance capacitors Much more reliable

Collimator installation and commissioning


Proton DemandProton Demand

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Q12002

Q22002

Q32002

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Q32004

Q42004

Q12005

Q22005

Q32005

Q42005

Q12006

Q22006

prot

ons

per h

our (

E16)

ShortfallBooster StretchBooster BaseNuMIpbar production

Booster Maximum ( loss limit)

MiniBooNE Turn-on

NuMITurn-on

Now(Note I mprovement!)

This is a goal, not a promise!!!

Have now exceeded initial NuMI needs!!!!

7.5 Hz


How far have we come?How far have we come?

Typical: 5.5E12 protons/batch to stacking (Run II handbook = 5E12) >7E16 pph to MiniBooNE (MiniBooNE goal 9E16)

Records: 6E12 protons/batch to stacking 8E16 pph to MiniBooNE

Time (s)

Oct. 2002 (MB turn-on) Jan. 2004

Energy LostCharge through Booster cycle

Now

http://www-bd.fnal.gov/cgi-mach/machlog.pl?nb=booster04&action=view&page=-1749&button=yes&invert=yes


Effect of increased intensity (recent running)Effect of increased intensity (recent running)

Energy Lost per proton

Protons per pulse

4E12 5E12

~5% more losses (activation) at 5E12

Can really deliver 5E12 efficiently for the first time!!!!!


Activation History In BoosterActivation History In Booster

MiniBooNE

16x proton increase

x2~3 activation

Collimators


Effect of CollimatorsEffect of Collimators

Booster Losses w/collimators (pre-shutdown)

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Location

Extraction

Ramp

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Collimators

Notch Loss

L13

L3 RF Region

Prompt Loss

After Collimators

Booster Losses w/o collimators

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e


Effect of Collimators by RegionEffect of Collimators by Region

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S1 (NOcols)

S1 (w/cols)

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Notch (w/cols)

CollimatorRegion

(NO cols)

CollimatorRegion(w/ cols)

Period 13(NO cols)

Period 13(w/ cols)

RFCavities

(NO cols)

RFCavities(w/ cols)

Rest (NOcols)

Rest(w/cols)

ExtractionRampInjection


Change In Activation Since CollimatorsChange In Activation Since CollimatorsSince Collimators

-100

-50

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L1 S1 S2Bex

2 S4 S5

L6 do

wn

L7 do

wn S8L1

0S11

S12 L13

S13

L14_R

F2_us L1

5

L15_R

F4_ds

L16_R

F5_ds S16

L17_R

F8_us L1

8

L19_R

F17_d

sS19 L2

1

L21_R

F10_d

s

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RF11_d

sS22

L23_R

F14_u

sL2

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L24_R

F16_d

s

Location

(per

cent

cha

nge)

Collimatorregion

RF Region

L13Extraction

L3 Extraction


Activation in RF Cavities – Big Success!!Activation in RF Cavities – Big Success!!

MiniBooNE

Collimators

Pre-MiniBooNE levels!!


Basis of activation assessment - Dose to WorkersBasis of activation assessment - Dose to Workers

Administrative limit at 300 mRem/qtr

This is “ok”, but we don’t want to get any worse

PA Shop by Qtr

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1st 02 2nd 02 3rd 02 4th 02 1st 03 2nd 03 3rd 03 4th 03 1st 04

Qtr and Year

mre

m

MiniBooNE


Status before shutdownStatus before shutdown Exceeding Run II intensity goals Can deliver 5E12 protons per batch with good

efficiency Regularly delivering ~80% of MiniBooNE goal Demonstrated NuMI intensities. Headroom left for at least some 8 GeV line

operation.


Major Performance-related Shutdown ProjectsMajor Performance-related Shutdown Projects Modify L13 extraction region:

Overall ~5 reduction in original “dogleg effect” Factor of 3 reduction over present effect

Adding 19th RF cavity: Use large aperture prototype Increase maximum batch size (~6.5E12) Increase reliability (can run with one failure)

Prep. for 20th cavity next year Complete modern laser tracker 3D network

and as-found in the Booster and 400 MeV line: Will be used to fully align the Booster next year

Move “pinger” girder to period 5: Extraction pre-notch will now fire into collimators Phased to aid extraction at both extraction regions!


Issues for the Longer TermIssues for the Longer Term Linac

Quad supplies very old, reliability concern. Unstable filament current has been a recurring

problem. In general, instrumentation is inadequate,

particularly in the Low Energy Linac (LEL). LEL LLRF in need of an upgrade. Nothing planned which will dramatically increase

peak performance.


Issues (cont’d)Issues (cont’d) Booster

Injection bump system (ORBUMP) must be replaced (discussed shortly).

• Will affect both rep. rate and performance Alignment RF

• Reliabilty• Power

Instrumentation• Existing system limited, inconsistent, and not

compatible with 15 Hz operation


Issues (cont’d)Issues (cont’d) Main Injector

Aperture RF

• Existing RF not powerful enough for potential protons from Booster


ORBUMP ReplacementORBUMP Replacement The existing injection bump (ORBUMP) system has

several major problems: Magnet and power supply heating limit the average rep.

rate to ~7.5 Hz. The system is not powerful enough to bump the beam the

required amount, resulting in close to a centimeter of horizontal beam slewing at injection!

Power supply switch network based on a large number (48) of obsolete SCR’s. Maintenance an issue.

Working on a new magnet and power supply: Magnets based on ferrite. Heating not an issue. New power supply.

• Higher rate capacitors• Modern SCR network• Modern charging controller

Entire system good for full 15 Hz Powerful enough to eliminate injection slewing.

Hope to be ready to install early to mid 2005.


Booster AlignmentBooster Alignment It has long been realized that there are

significant alignment problems in the Booster. These cause losses both through aperture

reduction and beam motion. Last year’s vertical as-found uncovered

significant problems, which were addressed. Over the shutdown, we are in the process of a

full laser-tracker 3D network and as-found of the Booster.

We will use that information over the next year to come up with an optimum set of horizontal moves.


Booster RF Cavity Options ConsideredBooster RF Cavity Options Considered Move forward with 5” prototype design?

Design complete and tested Could begin procurement and construction

immediately in FY05. Aggressive schedule could have cavities in place by

2007 Cost: ~6M

Completely new design? Could be designed with higher GE voltage and

reduced HOM. Frequency range a challenge Could have design by end of 2005, cavities in place

by 2008 Control losses with alignment and collimators?

Based on our successes to date, it appears we can Don’t replaceThis is my preliminary

recommendation


Solid State RF driversSolid State RF drivers Existing system is by far our biggest

maintenance item. Usually the older PA’s Average 1½ per month out of 17 cavities -> MTBF of

1 year. >$400K just for replacement cascode tubes. The technicians who service these tubes receive

some of the highest average radiation doses at the lab.

Newer solid state tubes much more reliable MTBF of at least 3 years. More or less identical to MI Prototype running in Booster for three years. Upgrade can be combined with necessary Main

Injector Upgrade.


Corrector PackagesCorrector Packages The Booster contains corrector packages at

each of the 48 sub-periods. Horizontal trim Vertical trim Quad Skew quad

The trims are not powerful enough to control the orbit throughout the cycle

The quads are not powerful enough to fully control the tune/coupling throughout the cycle


Corrector Package Specifications – Position Corrector Package Specifications – Position ControlControl

Observed Beam Motion and Slew Rate

Specification: Motion: +- 1 cm of motion at all fields Slew rate: 1 mm/ms at all fields


Corrector Specifications – Tune ControlCorrector Specifications – Tune Control Observed tune variation:

Specification: Tune: +- .1 unit of tune at all energies Slew rate: .01 unit/ms at all energies


Corrector SpecificationsCorrector Specifications Field specifications:

Roughly 3-4 times present system

Type Max. Field Max. Slew Rate

Horizontal Trim .009 T-m .5 T-m/s

Vertical Trim .015 T-m .8 T-m/s

Quadrupole .08 T-m/m 8 (T-m/m)/s

Skew Quadrupole Same as now Same as now


Booster InstrumentationBooster Instrumentation The existing Booster instrumentation is a mish-mash of

different technologies Most devices are read out through MADC channels

• Limited by C190 multiplexing• Not capable of reliable 15 Hz operation.

The BPM’s are read out through a dedicated digitization system;

• Capable of turn-by-turn readout of the entire system, BUT• Very slow to read out entire system.• Non-standard data interface complicates analysis.• Existing digitizers no longer available.

BLM system read out by IRM system:• Good to full 15 Hz.• No channel limit.• Is there something better now?

Plan Work with instrumentation this year to determine the best

solution for Booster readout, capable of snapshotting the entire Booster on and event-by-event basis.


Higher Harmonic OperationHigher Harmonic Operation By adding a 30 Hz compononent to the Booster

magnetic lattice, we could reduce the maximum dp/dt by ~35%, effectively increasing the RF power.

Pursue prototype in 2005 If successful, implement in 2006


Main Injector RF Power IssuesMain Injector RF Power Issues0 1E+13 2E+13 3E+13 4E+13 5E+13 6E+13 7E+13 8E+13

1 pBar + 5 NuMI @ 5E12




2 pBar + 10 NuMI @ 5E12

2 pBar + 10 NuMI @ 6E12

Total Protons

Baseline 2005 Operation

Single PA RF Power Limit

Possible during 2005

Goal for 2006


Booster/MI RF Upgrade ProjectBooster/MI RF Upgrade Project Goals:

Replace Booster PA’s with solid state versions, of the type used in the Main Injector.

Add a second PA to each Main Injector cavity. Plan:

Construct new PA’s and solid state drivers• 20 for Booster• 20 for second MI port.

Build new modulators for MI dual PA cavities: Move old MI modulators to Booster.


Money – Combined RF UpgradeMoney – Combined RF Upgrade

Element Unit Cost Total Max FY05 ProcurementSolid State Drivers (40) 110 4400 3200PA's (40) 100 4000 4000Modulator (20) 125 2500 1740

Totals: 10900 8940

Solid State RF Upgrade (Main Injector + Booster)

These are the projected total costs, and the maximum useful procurement money in FY05.

This spending profile could have a complete system in place in both machines at the end of FY06.


Other ProjectsOther Projects Linac

Quad Supplies: 250K Improved Instrumentation: 100K Filament Stabilization: 100K Laser chopping R&D: 100K Source R&D: 50K Subtotal: 600K

Booster ORBUMP Power Supply: 200K 30Hz Harmonic prototype: 50K Corrector Upgrade: 200K New Pinger System: 100K Instrumentation R&D: 100K Subtotal 650K

Total: 1250K Proposal: Fund these projects and as much of the RF

Upgrade as we can.


Approximate TimelineApproximate Timeline 2004

Collimators commissioned and fully operational L13 Modification Vertical and RF cavity alignment Complete alignment network and as-found 19th RF cavity added to Booster

2005 New ORBUMP magnets and Power supplies. Horizontal alignment Procurement for solid state PA’s Design and procurement for new corrector system Begin new quad supplies for linac Design and procurement for new Booster instrumentation

2006 Complete installation of solid state PA’s (fast track) Fabricate new corrector system Install 30 Hz harmonic, if recommended

2007 Complete new corrector system


High Rate Booster OperationHigh Rate Booster Operation Once the ORBUMP is upgraded, the entire

Booster will be capable of running at 15Hz, with the exception of the RF system.

Drift tube cooling and general maintenance should allow the RF system to reach 10 Hz. This is enough for:

• 2 pBar batches + 5 NuMI batches every 2 seconds +• FULL 5Hz MiniBooNE operation.

After that, we become limited by power from the mains, so if we decide to address it, it would naturally become part of the overall feeder upgrade plan.


Proton Projections - BoosterProton Projections - Booster Losses in the Booster continue to be the major

limitation to total proton throughput. It is extremely difficult to make quantitative

projections, so most projections are based on historical performance.

We have now come to a point where we believe we understand the performance well enough that quantitative projections will be possible in the not-too-distant future.

A lot of ground work has been done: In particular, the work to correlate activation to

beam loss.


Completion of Dogleg WorkCompletion of Dogleg Work Caused by parasitic focusing of dogleg magnet

Goes like square of bend angle. Both extraction regions ~ add.

Original magnitude: Max horizontal beta goes from 33 -> 47 m Max horizontal dispersion goes from 3.1 -> 6m

Solution Spread out dogleg magnets separation by >2.

Effect of L3 fix Decrease distortion from that side by ~5. Total distortion 60% of original (50% + 50%/5)

Effect of L13 fix Decrease remaining distortion by ~5 Total effect 20% of original. Factor of three better than prior to shutdown.

Conclusion: After this shutdown, the Booster will be much closer to an ideal machine.


Understanding Booster LossesUnderstanding Booster Losses

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L1 L2 L3 L4 L5 L6 L7 L8 L9 L10

L11

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L13

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L17

L18

L19

L20

L21

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L24

Location

Extraction

Ramp

Injection

Collimators

Notch Loss

L13

L3 RF Region

Prompt Loss

After Collimators


Understanding Booster LossesUnderstanding Booster Losses

Misalignment Will align this year

Lattice slewing Will improve after L13 work

Intentional L13 scraping Will move to collimators after

lattice is improved

Misalignment Will align this year

Injection mismatch: 400 MeV line work

Lattice distortion Improved after L13 work

Horizontal Slewing Eliminated with new ORBUMP

Notch Will move to collimators after

shutdown

Injection59%

Ramp40%

Extraction1%


Quantifying Booster LossQuantifying Booster Loss Main areas to understand:

Operation of the collimators• Helping, but still at least a factor of five away from

initial predictions.• It’s clear that up until now, the Long 13 aperture has

complicated collimator operation.• We are working to model this.

Beam loss related to beam position and size.• Because we don’t have a good model of Booster beam

halo, it’s difficult to quantitatively relate beam loss to things like beam position and beam size.

• Now that the loss pattern has become simplified, we should be able to quantify this through a series of straightforward aperture studies, beginning with the end of the shutdown.

Potential for 30Hz harmonic:• Can study by running at a lower energy.• Planned for shutdown.


Summary and ConclusionsSummary and Conclusions The Proton Source has made remarkable

progress thanks to the work of countless people.

We believe we have a realistic plan to optimize the reliability and performance of the system over the next few years.

The main part of this plan involves the RF systems of the Booster and Main Injector, and the timescale of these projects is completely determined by how fast we spend money on them.

proton plan

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